The objective of the proposed research is to evaluate ribosomal fractions from Streptococcus mutans for use in an anti-caries vaccine. Ribosomes will be obtained from strain GS-5 and injected into rabbits solely, as well as in combination with purified glucosyltransferase (GTF) enzymes. The antisera will be characterized in terms of their ability to: adhere to and agglutinate serotype c cells, prevent adherence of the bacteria, inhibit GTF activity, react with mammalian tissues and provide cross-serotype protection. Once the nature of the immunogen and antibody response has been determined in rabbits, the ability of the vaccine to prevent dental caries will be tested in rats. Significance: Ribosomal preparations may provide a safe and effective anti-caries vaccine when used alone or act as an adjuvant when used with purified glucosyltransferase enzymes.